diff --git a/src/Symfony/Component/ExpressionLanguage/ExpressionFunction.php b/src/Symfony/Component/ExpressionLanguage/ExpressionFunction.php
index 7408ff2fcf..18f7296d3e 100644
--- a/src/Symfony/Component/ExpressionLanguage/ExpressionFunction.php
+++ b/src/Symfony/Component/ExpressionLanguage/ExpressionFunction.php
@@ -84,12 +84,12 @@ class ExpressionFunction
             throw new \InvalidArgumentException(sprintf('An expression function name must be defined when PHP function "%s" is namespaced.', $phpFunctionName));
         }
 
-        $compiler = function () use ($phpFunctionName) {
-            return sprintf('\%s(%s)', $phpFunctionName, implode(', ', \func_get_args()));
+        $compiler = function (...$args) use ($phpFunctionName) {
+            return sprintf('\%s(%s)', $phpFunctionName, implode(', ', $args));
         };
 
-        $evaluator = function () use ($phpFunctionName) {
-            return $phpFunctionName(...\array_slice(\func_get_args(), 1));
+        $evaluator = function ($p, ...$args) use ($phpFunctionName) {
+            return $phpFunctionName(...$args);
         };
 
         return new self($expressionFunctionName ?: end($parts), $compiler, $evaluator);
diff --git a/src/Symfony/Component/Filesystem/Filesystem.php b/src/Symfony/Component/Filesystem/Filesystem.php
index 49c6f70d62..35c568e71e 100644
--- a/src/Symfony/Component/Filesystem/Filesystem.php
+++ b/src/Symfony/Component/Filesystem/Filesystem.php
@@ -717,14 +717,16 @@ class Filesystem
     }
 
     /**
+     * @param mixed ...$args
+     *
      * @return mixed
      */
-    private static function box(callable $func)
+    private static function box(callable $func, ...$args)
     {
         self::$lastError = null;
         set_error_handler(__CLASS__.'::handleError');
         try {
-            $result = $func(...\array_slice(\func_get_args(), 1));
+            $result = $func(...$args);
             restore_error_handler();
 
             return $result;
diff --git a/src/Symfony/Component/Finder/Finder.php b/src/Symfony/Component/Finder/Finder.php
index 65154ef2f2..b5a3b964db 100644
--- a/src/Symfony/Component/Finder/Finder.php
+++ b/src/Symfony/Component/Finder/Finder.php
@@ -20,6 +20,7 @@ use Symfony\Component\Finder\Iterator\DepthRangeFilterIterator;
 use Symfony\Component\Finder\Iterator\ExcludeDirectoryFilterIterator;
 use Symfony\Component\Finder\Iterator\FilecontentFilterIterator;
 use Symfony\Component\Finder\Iterator\FilenameFilterIterator;
+use Symfony\Component\Finder\Iterator\LazyIterator;
 use Symfony\Component\Finder\Iterator\SizeRangeFilterIterator;
 use Symfony\Component\Finder\Iterator\SortableIterator;
 
@@ -622,7 +623,9 @@ class Finder implements \IteratorAggregate, \Countable
 
         $iterator = new \AppendIterator();
         foreach ($this->dirs as $dir) {
-            $iterator->append($this->searchInDirectory($dir));
+            $iterator->append(new \IteratorIterator(new LazyIterator(function () use ($dir) {
+                return $this->searchInDirectory($dir);
+            })));
         }
 
         foreach ($this->iterators as $it) {
diff --git a/src/Symfony/Component/Finder/Iterator/LazyIterator.php b/src/Symfony/Component/Finder/Iterator/LazyIterator.php
new file mode 100644
index 0000000000..9028facf7f
--- /dev/null
+++ b/src/Symfony/Component/Finder/Iterator/LazyIterator.php
@@ -0,0 +1,30 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Finder\Iterator;
+
+/**
+ * @author Jérémy Derussé <jeremy@derusse.com>
+ */
+class LazyIterator implements \IteratorAggregate
+{
+    private $iteratorFactory;
+
+    public function __construct(callable $iteratorFactory)
+    {
+        $this->iteratorFactory = $iteratorFactory;
+    }
+
+    public function getIterator(): \Traversable
+    {
+        yield from ($this->iteratorFactory)();
+    }
+}
diff --git a/src/Symfony/Component/Finder/Tests/Iterator/LazyIteratorTest.php b/src/Symfony/Component/Finder/Tests/Iterator/LazyIteratorTest.php
new file mode 100644
index 0000000000..1a96c32d0b
--- /dev/null
+++ b/src/Symfony/Component/Finder/Tests/Iterator/LazyIteratorTest.php
@@ -0,0 +1,53 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Finder\Tests\Iterator;
+
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Finder\Iterator\LazyIterator;
+
+class LazyIteratorTest extends TestCase
+{
+    public function testLazy()
+    {
+        new LazyIterator(function () {
+            $this->markTestFailed('lazyIterator should not be called');
+        });
+
+        $this->expectNotToPerformAssertions();
+    }
+
+    public function testDelegate()
+    {
+        $iterator = new LazyIterator(function () {
+            return new Iterator(['foo', 'bar']);
+        });
+
+        $this->assertCount(2, $iterator);
+    }
+
+    public function testInnerDestructedAtTheEnd()
+    {
+        $count = 0;
+        $iterator = new LazyIterator(function () use (&$count) {
+            ++$count;
+
+            return new Iterator(['foo', 'bar']);
+        });
+
+        foreach ($iterator as $x) {
+        }
+        $this->assertSame(1, $count);
+        foreach ($iterator as $x) {
+        }
+        $this->assertSame(2, $count);
+    }
+}
diff --git a/src/Symfony/Component/Intl/Tests/Locale/AbstractLocaleTest.php b/src/Symfony/Component/Intl/Tests/Locale/AbstractLocaleTest.php
index cf991c9bcc..a3daecb59e 100644
--- a/src/Symfony/Component/Intl/Tests/Locale/AbstractLocaleTest.php
+++ b/src/Symfony/Component/Intl/Tests/Locale/AbstractLocaleTest.php
@@ -27,5 +27,10 @@ abstract class AbstractLocaleTest extends TestCase
         $this->assertSame('en_GB', $this->call('getDefault'));
     }
 
-    abstract protected function call($methodName);
+    /**
+     * @param mixed ...$args
+     *
+     * @return mixed
+     */
+    abstract protected function call(string $methodName, ...$args);
 }
diff --git a/src/Symfony/Component/Intl/Tests/Locale/LocaleTest.php b/src/Symfony/Component/Intl/Tests/Locale/LocaleTest.php
index 80b3352e21..05ba7106eb 100644
--- a/src/Symfony/Component/Intl/Tests/Locale/LocaleTest.php
+++ b/src/Symfony/Component/Intl/Tests/Locale/LocaleTest.php
@@ -139,10 +139,8 @@ class LocaleTest extends AbstractLocaleTest
         $this->assertSame('en', $this->call('getDefault'));
     }
 
-    protected function call($methodName)
+    protected function call(string $methodName, ...$args)
     {
-        $args = \array_slice(\func_get_args(), 1);
-
         return Locale::{$methodName}(...$args);
     }
 }
diff --git a/src/Symfony/Component/Intl/Tests/Locale/Verification/LocaleTest.php b/src/Symfony/Component/Intl/Tests/Locale/Verification/LocaleTest.php
index 45c90f6c0f..c0b1b26b62 100644
--- a/src/Symfony/Component/Intl/Tests/Locale/Verification/LocaleTest.php
+++ b/src/Symfony/Component/Intl/Tests/Locale/Verification/LocaleTest.php
@@ -29,10 +29,8 @@ class LocaleTest extends AbstractLocaleTest
         parent::setUp();
     }
 
-    protected function call($methodName)
+    protected function call(string $methodName, ...$args)
     {
-        $args = \array_slice(\func_get_args(), 1);
-
         return \Locale::{$methodName}(...$args);
     }
 }